Re: Memory exhaustion on large query

Many thanks for your help.

A call to PQsetSingleRowMode just after PQsendQueryPrepared solved my issue.

Regards,
Brice

Le dim. 12 déc. 2021 à 19:43, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> a écrit :

> =?UTF-8?B?QnJpY2UgQW5kcsOp?= <brice(at)famille-andre(dot)be> writes:
> > The content of the table is so huge that, if PQsendQueryPrepared
> retrieves
> > all data, or if postgresql engine is creating temp file with all data,
> the
> > query cannot succeed (I have no enough RAM or disk space to copy the
> whole
> > data). But I was expecting that using PQsendQueryPrepared and PQgetResult
> > would avoid this by returning one result at a time.
>
> You're confusing asynchronous mode with single-row mode. Async mode,
> per se, doesn't change memory consumption; it just lets you do something
> else while waiting for the query result. You are (I suppose) missing
> a call to PQsetSingleRowMode --- see
>
> https://www.postgresql.org/docs/current/libpq-single-row-mode.html
>
> regards, tom lane
>